The present invention is directed to an electronic battery sensor and a method for determining an internal resistance of a battery. A method for reconstructing an electrical signal is described in PCT Patent Application No. WO 2006/037694. In this method, an analog measuring signal is sampled at a high sampling rate with the aid of an analog-digital converter. The voltage and current intensity of a battery, for example, are used here as measuring signals, from which an internal resistance may be subsequently computed. The internal resistance is computed by dividing a voltage difference by a current intensity difference. In addition, prior to the sampling the measuring signal is generally low-pass filtered in order to adhere to the sampling theorem. The occurrence of aliasing may be avoided in this way. In the described method, the current signals and voltage signals necessary for computing the internal resistance are detected by a current sensor and a voltage sensor, respectively.
An object of the present invention is to allow a high sampling rate, and at the same time, to avoid a long computing time for computing the internal resistance.